A series of experiments were designed to test the hypothesis, postulated in our former report, on conditions necessary for the instantaneous judging of the number of objects. In this study, particularly spatial arrangements of objects were examined.<br>Stimulus cards; Ninety-one cards of different figural patterns were used. Some of them contained outline circles of 1cm in diameter and others vertical lines of 1cm in length as stimulus objects. They were arranged in a horizontal row, but varied in number (from 1 to 10) and in amount of interval.<br>Subjects & procedure; For each of 6 experiments, from 7 to 10 adults were subjected to the tachistoscopic presenta tion of the cards to measure the time value of cognition threshold.<br>Purpose of each experiment; I. To test the effect of the distance between two stimulus objects. (Exp. I)<br>II. To test the effect of two-subdividing arrangements of objlcts at a constant range, within which they were arranged. (See Fig. 2-1) (Exp. II)<br>III. To test the effect of the amount of interval when the stimulus objects were arranged homogeneously (i.e., equidistantly). (Exp. III)<br>IV. To test the effects of subdivisional arrangements such as follws;<br>i) When the stimulus objects were articulated into two subgroups, the one of which contained the same number of objects as the other or one more than the other. (Exp. IV)<br>ii) When they were articulated into three subgroups, each of which contained two or three objects. (Exp. V)<br>iii) When they were articulated into subgroups, each of which contained two or less objects. (Exp. VI)<br>Results; The results obtained are shown in Fig. 1, 2-2, 3, 4, 5 and 6. From these results, following conditions were found to be favourable for the instantaneous judging of the number of objects.<br>1. The objects are to be not too close to each other, but to be spaced out appropriately.<br>2. The objects are to be articulated into some sub-groups, rather than to be arranged equidistantly.<br>3. Each of those sub-groups is to contain two or less objects.<br>4. The number of those sub-groups is to be three or less.<br>Discussion; So far as the instantaneous judging of the number of objects by normal adults are concerned and if the number of objects is six or less, all above mentioned conditions derived from this study can be satisfied simultaneously regardless of their arrangements, i.e., whether or not they are divided into some sub-groups or placed homogeneously.<br>If the number exceed six, however, all these conditions cannot be always satisfied simultaneously even if the stimulus objects were divided into sub-groups. Therefore, this may be a reason why the number “six” has long been accepted as the socalled “range of attention”.